What's new in h5py 3.12
=======================

New features
------------

* h5py now has pre-built packages for Python 3.13.

  * However, h5py is not yet compatible with the new free-threading mode;
    we're tracking work on that in issue :issue:`2475`.

Breaking changes
----------------

* Support for Python 3.8 was dropped (:pr:`2471`). Python 3.9 or newer is
  required to build or install h5py 3.12.
* The minimum supported version of HDF5 was increased to 1.10.6 (:pr:`2486`).
  If you need h5py on HDF5 1.10.4 or .5, please use h5py 3.11.
* The fill time for chunked storage was previously set to ``h5d.FILL_TIME_ALLOC``.
  Now this the default comes from HDF5, which uses ``h5d.FILL_TIME_IFSET``
  (equivalent to ``fill_time='ifset'``) (:pr:`2463`). Please use
  ``fill_time='alloc'`` if the change is a problem for you.

Exposing HDF5 functions
-----------------------

* Expose fill time option in dataset creation property list via the
  ``fill_time`` parameter in :meth:`~.Group.create_dataset` (:pr:`2463`).

Bug fixes
---------

* Fix an error where native float16 support is not available (:pr:`2422`).
* Fixed values of ``H5F_close_degree_t`` enum (:pr:`2433`).
* External links are now accessed with libhdf5's default access properties
  (:pr:`2433`).
* Fix the iteration order for the root group in a file with creation order
  tracked (:pr:`2410`).
* Fixed some deprecation warnings from NumPy (:pr:`2416`).

Building h5py
-------------

* Require a newer version of mpi4py for Python 3.12 (:pr:`2418`).
* The test suite is now configured to fail on unexpected warnings (:pr:`2428`).
* The generated Cython wrapper code (``defs.*`` & ``_hdf5.pxd``) is now specific
  to the version of HDF5 it's building for. If the version of HDF5 has changed,
  ``api_gen.py`` should be run automatically to recreate this (:pr:`2479`,
  :pr:`2480`).
* Various PRs modernising & cleaning up old Cython code, see the `3.12 milestone
  on Github <https://github.com/h5py/h5py/milestone/31?closed=1>`_ for details.

3.12.1 bug fix release
----------------------

* Fix bundling HDF5 DLLs in pre-built packages for Windows (:pr:`2507`).